1. Field of the Invention
The present disclosure relates generally to a device and method for lung function diagnosis, and more particularly to a device and method for non-cooperative lung function analysis using flow and molar mass data from ultrasonic transit time measurements during quiet breathing with a portable spirometer.
2. Description of Prior Art
There are several systems described for lung function diagnosis based on the analysis of flow (and therefore volume, determined by integration of the flow) combined with a gas analysis signal, e.g., You et al. “Expiratory Capnography in Asthma: Evaluation of Various Shape Indices” (Eur Respir J., 7; 318-323, 1994) and Krauss et al. “Capnogram Shape in Obstructive Lung Disease” (Anesth Analg, 100:884888, 2005). All systems use separate gas analysis devices for measuring the CO2 concentration, e.g. mass spectrometers or devices based on infrared absorption. In some cases defined breathing maneuvers are used.
Generally, most of the lung function tests in primary care are performed by executing so-called “forced” expiratory maneuvers. During such a test, a patient must fully inhale and then perform a sudden, forced expiration until no more gas can be exhaled. The test may be followed by a forced inspiratory maneuver. Analysis of the flow over a volume graph and/or volume over a time graph results in a set of parameters that are used for lung function diagnosis. To perform such a test, the procedure must be explained to the patient in detail and the patient must follow the guidelines of the test with great care. Generally, the tests must be repeated at least three times to obtain a measure of sufficient test quality. The tests are relatively difficult to explain and also exhausting for the patient. Furthermore, the test can only be performed successfully if the technician performing the test is well trained.
Many other medical tests that are used for screening, for example, measuring of blood pressure or electrocardiogram (ECG), do not require this type of patient cooperation.
Accordingly, it is an object to improve pulmonary diagnostic testing and analysis.
It is a more specific object of the present invention to improve such pulmonary diagnostic testing and analysis minimizing discomfort of a patient being tested.
It is a further object of the present invention to expedite and simplify pulmonary diagnostic testing and analysis.
It is a further more specific object of the present invention to both improve ease of the pulmonary diagnostic testing and analysis for an administering technician or medical personnel and at the same time minimize instructions to a patient being tested.
It is another object of the present invention to provide effective pulmonary diagnostic testing and analysis of a patient without need for the patient's active intervention, e.g., while the patient might be unconscious or otherwise unable to cooperate.